Generally, various electric cables for signal communication and power supply etc. to an electronic apparatus are used in the condition where the electric cables are exposed to steady noises such as electro-magnetic wave and/or vibrations. When the electric cable receives such external noises, the signals under communication may be disturbed and erroneous actions may take place in a precise electronic apparatus such as a computer in the worst case.
In order to suppress the influence of the external noises as describe above, it has been so far proposed to shield the electric cable. In this regard, Japanese Patent (Laid-Open) No. 2004-63418 (Patent Literature 1) discloses a parallel dual line shielded cable to which a shield layer is formed by winding spirally thereon a metal sheet tape such as an Al-PET tape or a copper-deposited PET tape. Such metal sheets could provide certain shield effects for the electro-magnetic wave; however, it has been insufficient with respect to a vibration absorption effect. An improved shield performance has still been expected as a performance of electronic apparatuses, a speed of the signal communication, and a high density implementation of wirings in the apparatus and the like are improved.
In addition, for the electric cable such as an AV (Audio Visual) cable, which is required to transmit delicate analog signals as faithfully as possible, influence of the external noises is clearly reflected to qualities of outputs (sound quality and/or image quality), and then the external noises must be reduced to the limit as low as possible. Moreover, when the shield layer of the audio cable is constructed by using a copper sheet or an aluminum sheet, the technical problem that incongruity on timbre of the output sounds (i.e., so called overlap of metallic sounds) has been caused because resonance components being unique to the above metal materials are migrated to the sound signals.